m6A mRNA modifications are deposited in nascent pre-mRNA and are not required for splicing but do specify cytoplasmic turnover.
Genes Dev
; 31(10): 990-1006, 2017 05 15.
Article
em En
| MEDLINE
| ID: mdl-28637692
ABSTRACT
Understanding the biologic role of N6-methyladenosine (m6A) RNA modifications in mRNA requires an understanding of when and where in the life of a pre-mRNA transcript the modifications are made. We found that HeLa cell chromatin-associated nascent pre-mRNA (CA-RNA) contains many unspliced introns and m6A in exons but very rarely in introns. The m6A methylation is essentially completed upon the release of mRNA into the nucleoplasm. Furthermore, the content and location of each m6A modification in steady-state cytoplasmic mRNA are largely indistinguishable from those in the newly synthesized CA-RNA or nucleoplasmic mRNA. This result suggests that quantitatively little methylation or demethylation occurs in cytoplasmic mRNA. In addition, only â¼10% of m6As in CA-RNA are within 50 nucleotides of 5' or 3' splice sites, and the vast majority of exons harboring m6A in wild-type mouse stem cells is spliced the same in cells lacking the major m6A methyltransferase Mettl3. Both HeLa and mouse embryonic stem cell mRNAs harboring m6As have shorter half-lives, and thousands of these mRNAs have increased half-lives (twofold or more) in Mettl3 knockout cells compared with wild type. In summary, m6A is added to exons before or soon after exon definition in nascent pre-mRNA, and while m6A is not required for most splicing, its addition in the nascent transcript is a determinant of cytoplasmic mRNA stability.
Palavras-chave
Texto completo:
1
Coleções:
01-internacional
Base de dados:
MEDLINE
Assunto principal:
RNA Mensageiro
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Precursores de RNA
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Splicing de RNA
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Citoplasma
Limite:
Animals
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Humans
Idioma:
En
Revista:
Genes Dev
Assunto da revista:
BIOLOGIA MOLECULAR
Ano de publicação:
2017
Tipo de documento:
Article
País de afiliação:
Estados Unidos